MATT MULLICAN loves to scribble. “This is my studio,” he said on a recent morning, gesturing around the fluorescent-lighted space in Lower Manhattan that serves as a workshop, office, storage room and clearinghouse for his artwork. “But I don’t really work here. My studio is in my notebook, and where I travel.”

As if to prove the point, he plucked a sketchbook off a metal bookshelf and opened it.

A Christmas gift from his parents dated Dec. 26, 1970, it was filled in a single day by Mr. Mullican, now 57, when he was still a high school senior. A miniature tour of Pop Art history, it is strikingly precocious.